We are analyzing the endocrine and genetic control mechanisms that regulate insect development. We are particularly concerned with the development of Drosophila, since this organism offers the opportunity to use genetic mutations and techniques in the analysis. Our work is concerned with basic developmental mechanisms but it could lead to the development of materials which could be used as insecticides. We are studying the formation and expansion of cuticle during Drosophila development, by electron microscopy and by the analysis of incorporation of precursors. We are also studying the effects of juvenile hormone on the development of both the integument and the internal organs. The origin of various adult structures from the abdominal histoblasts is being analyzed by clonal analysis. We propose to study the ability of regenerating tissues to cause pupariation delay in Drosophila. This could lead to the identification of a new endocrine control mechanism which might be exploitable in developing pest control techniques.